Infrared emitters and sensors are used in a variety of applications, such as air quality monitoring, exhaust gas analysis, glucose sensing, volatile agent sensing, process controls and monitoring, demand controlled ventilation, and enclosed space safety monitoring. Certain infrared emitters have been described, such as the emitter in U.S. Pat. No. 6,031,970; and the layered semiconductor-dielectric-metal structures in US 2007/0018077 and US 2007/0034978. However, there remains a need in the art for improved infrared sensors and emitters.